The Belgian Problem

Note: There are two achievements you can unlock here. I suggest keeping a separate save file.

Once ready, head back your crib to load up and roll out. Drive to the tower and start killing everybody. After clearing the area, arm the bomb and call the elevator. You have 16 minutes to complete your objective.

After disembarking from the elevator, follow the objective markers until you reach the upper platform. A brute with an Incenerator will appear. Keep distance and take him out. Continue heading upstairs and watch the following scene.

After that, call the elevator and follow Oleg. Continue upstairs and watch the scene. Kill the guards while dangling and the brute while you're in mid-air. You'll finally have the decide whether you want to blow the building up (permanent respect bonus) or disarm the bomb. (permanent cash bonus)